High-frequency coaxial cable outer conductor



Aug. 12, 1952 w. K. WESTON HIGH-FREQUENCY COAXIAL CABLE OUTER CONDUCTOR 2 SHEETS-SHEET 1 Filed Sept. 20, 1947 INVENTOR W K. WESTON ATTORNE Aug. 1952 w. K. WESTON 2,606,953

HIGH-FREQUENCY COAXIAL CABLE OUTER CONDUCTOR Filed Sept. 20, 1947 2 SHEETS-SHEET 2 FIG. 4A. FIG. 48. FIG. 4C.

INVENTOR W. K. WESTON 2 ATTORNEY Patented Aug. 12, 1952 HIGH-FREQUENCY COAX-IAL CABLE OUTER CONDUCTOR William'Kirby Weston, London, England, assignor to.InternationalStandard Electric Corporation, New York, N. Y., a corporation of Delaware Application September 28, 1947, Serial No. 775,217 In Great Britain September 23,1946

The present invention relates to electric cables for high frequency transmission and employing outer conductors formed of a tape or tapes of conducting material.

In the design of air spaced coaxial cable for wide band transmission, it is desirable to make the outer coaxial conductor of such dimensions that if this conductor is made in the form of a hollow tube, it remains suiiiciently flexible to enable it to be handled during manufacture and installation. For this reason it has been proposed to make the outer conductor of a thin corrugated tape, or tapes, the corrugations permitting of suflicient flexibility for the cable to be handled satisfactorily during manufacture and installation.

In the type of cable so far proposed, it has been necessary to support the corrugated tape continuously, or with but small gaps between the supporting members, in order to preserve the correct substantially cylindrical formation of the outer conductor. It has been found, however, that with a tape having corrugations of this type, the tube so formed could be made self-supporting, provided the abutting edges of the tape can be prevented from sliding one over the other. It will be apparent that if the corrugations are uniform across the width of the tape and at right-angles thereto, or even in the case of helical corrugations, the abutting edges will tend to slide over one another.

The present invention, in order to overcome this difficulty, consists in an air spaced coaxial cable having an outer conductor of corrugated tape or tapes formed to shape with the adjacent edges of said tape or tapes abutting and in which said corrugations are deformed along the butt joint or joints so that the tape edges cross one another at an angle.

In order to illustrate the invention, reference may be made to the accompanying drawings, in which:

Fig. l is an enlarged perspective View showing a portion of a cylindrical corrugated tape according to the prior art;

Fig. 2 is an enlarged perspective View showing a portion of a cylindrical tape in accordance with the present invention;

Fig. 3 is a plan view of a portion of a corrugated tape according to the present invention;

Figs. 4A, 4B and 4C are crcss-sectional views respectively along the lines A- 3-33 and C-C of Fig. 3;

Fig. 5 is a broken, elevational view of a portion of a coaxial cable in accordance with the present invention; and

2 Claims. (01. 174-.430)

Fig. "6 is an end view, partially in section, or the cable shown in Fig. -5.

Fig. 1 illustrates the old-type of cable previous ly mentioned from which it will be seen that in the case of a cable made from corrugated tape in the manner used up to now, the abutting edges of this tape will tend to slide over one another.

The improvement is illustrated in Fig. 2 of the accompanying drawings from which it will be seen that the tape I would have to be forced out of position by not the thickness of the tape, but by the total amplitude of the corrugations before the relatively displaced edges 11 and c could overlap. By this means it is possible to construct an air spaced coaxial cable without a continuous inner dielectric wall supporting the outer tape, the construction following any of the known methods of manufacture, such as the use of washers to support the central conductor in relation to the outer tape at intervals, the outer tape being bound externally to retain the two edges of the outer tape in contact with each other. In this Way, a coaxial cable is provided in which there is a reduced quantity of dielectric, since it is now only necessary to support the central conductor at intervals and a greater degree of uniformity of the outer conductor is obtained, since this is determined solely by the width of the original tape forming the outer conductor which can be made very accurately and also the degree of corrugating which can also be controlled.

A method of making the tape above described would be to pass the tape between two engaging toothed rollers, in which the major portion of the two rollers gives a sine wave corrugation to the central portion of the tape, whilst the edges have the sine wave distorted in one direction on one edge and in the opposite direction on the other edge to an equal amount.

The form of a preferred type of corrugation is illustrated in Figs. 3 and 4 of the accompanying drawings. The ridge of the corrugations formed on a flat tape are shown in Fig. 3, with the corrugations at one end displaced in one direction as at la and the corrugations at the other-end displaced in the opposite direction as at to. The profiles of sections along AA, BB and CC are shown at A, B and C respectively in Fig. 4. The relative dimensions are, of course, considerably exaggerated in both figures.

It will be evident that other Ways of distorting the contours and other shapes of contours may be used without departing from the scope of the invention.

After forming the corrugations the tape or tapes are formed onto the cable and bound with binding tapes in the normal way. As the outer conductor is now made self-supporting, comparatively thin insulating spacers may be used to support the inner conductor of the cable as indicated in Figs. 5 and 6 of the accompanying drawings, in which reference numeral 1 indicates the corrugated outer conductor butt jointed at 2 and bound round with metal tape 3. Insulators 4 support inner conductor 5, which may itself form the outer conductor of a further coaxial cable.

What is claimed is:

1. In a coaxial conductor cable, a hollow tubular conductor consisting of a thin cylindrical metal tube having longitudinally abutting edges, circumferential corrugations in said tube to render it flexible, corrugations at the abutting edges of the tube being respectively longitudinally displaced in opposite directions, whereby the abutting edges cross one another and relative circumferential movement therebetween is prevented.

2. Tubular conductor according to claim 1, in

4 which the corrugations are, longitudinally, substantially sinusoidal for the greater part of the circumference of the tube, but deformed at the abutting edges to provide said crossed abutting contact.

- WILLIAM KIRBY WESTON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 24,883 Montgomery July 26, 1859 689,280 Brown Dec. 17, 1901 999,390 McMartin Aug. 1, 1911 2,126,290 Seeley Aug. 9, 1938 2,165,737 Unterbusch July 11, 1939 2,223,116 Meyer et a1. Nov. 26, 1940 FOREIGN PATENTS Number Country Date 3,319 England Mar. 9, 1886 

